// 纯函数和不纯函数
// slice / splice

let array = [1, 2, 3, 4, 5];

// 纯函数
console.log(array.slice(0, 3));
console.log(array.slice(0, 3));
console.log(array.slice(0, 3));

// 不纯函数
console.log(array.splice(0, 3));
console.log(array.splice(0, 3));
console.log(array.splice(0, 3));

// 纯函数
function getSum(n1, n2) {
  return n1 + n2;
}
console.log(getSum(1, 2));
console.log(getSum(1, 2));
console.log(getSum(1, 2));
